OCCURRENCE OF BRONT MOSAIC VIRUS IN HWGATED WHEAT IN ZAMBIA
RG KAPOORIA and J NDUNGURU
Department of Biological Sciences, University of Zambia, Box 32379, Lusaka, Zambia
Background and objectives
Wheat cultivation under irrigation has been practised now for many years during the cooler months of Nlay-August in Zambia. At this time the crop enjoys relatively little pressure from bacterial and fungal diseases although certain diseases appear to be building up. However, country records do not show the occurrerice of virus diseases, their diversity and the extent of darriage, despite their importance in lowering wheat yields.
Bronic mosaic bronlovn-us (BMV) was reported in Bromus inermis in the U. S. A. and now the virus occurs in Europe, South Africa and Australia. The virus is known to attack wheat and cause significant yield loss. Its ,vinptom-s include prominent streak-like -cattle or, voting folin,- of infected plants which develop yellow-green n-iosaic. With ageing plants, the symptoms subside, particularly the yellow-green niottle. Mild stunting and head deformation can also occur . A study was therefore undertaken during the wheat growing season of 1977 to investigate the occurrence and distribution of Brome mosaic virus in several commercial farms.
Materials and methods
Field survey of wheat crop was conducted in the Ceilral, Lusaka and Southern provinces of Zambia during June-August 1997 and a total of 68 virus sait]es were collected from 11 fanris. The identification of the virus was based on BMV symptoms in field infected vaieat, its reaction on a panel of differential plants and serology (DAS ELISA) employing commercial kits.
Results and conclusions
Bronle mosaic virus was detected by the presence of yellow-green mosaic and large chlorotic lesions
at the nuddle of infected wheat leaves. Plants also showed moderate stunting and head defoliation.
BMV infected Chenopodium aniaranticolor, C. quinoa and C. hybridurn following mechanical iriocidation of these plarits in greenhouse. The virus caused systei-dc and local lesions on inoculated Sorghum bicolor, Triticum aestivwn and Zea mays . However, it did not infect Oryza sativa, Padcurn rra, Digitaria milanj iar3a and Setaria verticillata .
In this survey BMV was picked up in 37% Meat Ies and showed positive reaction to the BMV
antiserw-n in DAS ELISA test. This is the first report of this virus on wheat in Zambia.
1. Wiese MV, 1977. Compendium of heat disease. Ajwrican Phytopathological Swiety.